Distribution of growth-associated protein, B-50 (GAP-43) in the mammalian enteric nervous system

The presence of the growth-associated protein, B-50 (also known as GAP-43) was investigated in the adult mammalian enteric nervous system. The small intestine of rat, ferret and human was examined by immunohistochemistry. Dense B-50-like immunoreactivity was localized in nerves throughout the wall of the rat, ferret and human small intestine, notably in the myenteric and submucous plexuses, where in the ferret ileum it co-localized with vasoactive intestinal polypeptide-immunoreactive fibre groups. Material with the biochemical and immunological characteristics of rat B-50 was extracted from the rat ileum. In-situ hybridization demonstrated that enteric neurons express B-50. These findings are consistent with a role for B-50 in the documented plasticity of the adult enteric nervous system.     

Diffusion tensor imaging and mild parkinsonian signs in cerebral small vessel disease

Although the role of cerebral small vessel disease (SVD), including white matter lesions (WMLs) and lacunar infarcts, in mild parkinsonian signs (MPS) is increasingly being recognized, not all individuals with SVD have MPS. Using diffusion tensor imaging (DTI), we investigated whether the presence of MPS was dependent on the microstructural integrity underlying WMLs, the early loss of integrity of the normal-appearing white matter (NAWM) and location of this damage. We examined 483 elderly subjects with SVD and without parkinsonism. Subjects with severe loss of integrity within their WMLs had a higher risk of MPS, regardless of WML volume (fractional anisotropy odds ratios = 1.9; 95% confidence interval, 1.1-3.4). The same was found in the normal-appearing white matter, but this association disappeared after adjustment for WMLs and lacunar infarcts. The integrity of the periventricular frontal regions-of-interest was significantly lower in subjects with MPS than without, independent of WMLs and lacunar infarcts. This study indicates that integrity of WMLs, especially in the frontal lobe, is associated with MPS. Diffusion tensor imaging may be of added value in investigating the underlying mechanisms of parkinsonian signs in subjects with SVD.     

Human abdominal aorta: comparative measurements of blood flow with MR imaging and multigated Doppler US

Magnetic resonance (MR) imaging has proved to be a new alternative method for the noninvasive detection and quantification of blood flow in human vessels. By means of standard gradient echo sequences triggered with electrocardiography on a 1.5-T whole-body imaging system, the authors measured the flow-induced phase shift in the abdominal aorta of healthy volunteers. The instantaneous two-dimensional velocity profiles and the integrated flow rate were determined in intervals down to 21 msec throughout the cardiac cycle. The results were validated by means of comparative measurements with a multigated Doppler ultrasound instrument. The velocity values acquired with this instrument in one spatial dimension in the anteroposterior direction of the abdominal aorta agreed to a great extent with the temporal and spatial corresponding values recorded with MR imaging. The same high correlation between the two methods was found for the calculated instantaneous total blood flow.     

Revised guideline 'Vasectomy' from the Dutch Urological Association

Vasectomy is a simple and reliable method of contraception. Problems associated with vasectomy include inadequate patient information, complications of the procedure e.g. infection and scrotal bleeding (4-22%), chronic scrotal pain after the procedure (2-5%) and spontaneous recanalisation with return of fertility (0.03-I12%). Later in life a substantial number of men come to regret having a vasectomy, notably those who underwent it at a young age and those without children of their own. After 10 years 2.4% of vasectomised Dutch men have a refertilisation procedure (usually a vasovasostomy) because of the wish for children in a new relationship. Since vasectomy is an elective procedure and not done on medical indication, it requires an extensive informed-consent procedure for the patient. Insufficient information may result in inadequate follow-up, omission of semen analysis, and consequent legal procedures should complications or pregnancy ensue. Clearance after the first semen analysis at 3 months can be given if azoospermia is seen or if less than 100,000 non-motile spermatozoa are present in the ejaculate.     

Quantification of BNP7787 (dimesna) and its metabolite mesna in human plasma and urine by high-performance liquid chromatography with electrochemical detection

A sensitive and accurate assay was developed and validated to determine BNP7787 (dimesna), a new protector against cisplatin-induced toxicities, and its metabolite mesna in plasma and urine of patients. Both analytes were measured as mesna in deproteinized plasma or in urine diluted with mobile phase using high-performance liquid chromatography with an electrochemical detector provided with a wall-jet gold electrode. The assays for BNP7787 and mesna in deproteinized plasma were linear over the range of 1.6-500 microM and 0.63-320 microM, respectively. In plasma, the mean recovery of BNP7787 over the whole concentration range was 100.6% and of mesna 94.6%. The lower limits of quantitation (LLQs) of BNP7787 and mesna in deproteinized plasma were 1.6 microM and 0.63 microM, respectively. For both compounds the within- and between-day accuracy and precision of the assay was better than 12%. The assays for BNP7787 and mesna in urine were linear over the range of 0.8-1200 microM and 0.63-250 microM, respectively. In urine, the mean recovery of BNP7787 over the whole concentration range was 94.1% and of mesna 93.1%. The LLQ of BNP7787 in urine was 0.8 microM and of mesna 1.6 microM. The within- and between-day accuracy and precision of the assay for BNP7787 and mesna was lower than 15%. The stability of mesna in urine increased with an increasing concentration of mesna, lower temperature and addition of EDTA (1 g/l) and hydrochloric acid (0.2 M). BNP7787 in urine was stable for at least 24 h at temperatures in the range of -20 degrees C up to 37 degrees C and independent of the concentration. The developed assays are currently applied for samples of patients with solid tumors participating in a phase I trial of BNP7787 in combination with cisplatin.     

Dephosphorylation of B-50 in synaptic plasma membranes

Synaptic plasma membranes from rat brain cortex possess intrinsic ability to dephosphorylate the endogenous protein B-50. At low concentrations of [gamma-32P]ATP, B-50 phosphorylation in synaptic membranes is maximal at 30 seconds, followed by dephosphorylation for an additional 60 minutes. The dephosphorylation of 32P-labeled B-50 is not sensitive to the protease inhibitor leupeptin and not correlated with a loss of the B-50 content of synaptic membranes as measured with immunoblot analysis. Dephosphorylation of membrane-associated B-50 is stimulated to a small extent by Mg2+ but not by Ca2+. Heat-stable protein phosphatase inhibitors prevent dephosphorylation of 32P-labeled B-50. Dephosphorylation of B-50 in synaptic membranes is stimulated by ATP, ADP, or adenosine 5'-O-thiotriphosphate, but not by adenine, adenosine, other adenine or guanine nucleotides, nonhydrolyzable analogs of ATP or GTP, nor by adenosine 5'-O-(2-thiodiphosphate). B-50, phosphorylated by exogenous protein kinase C and purified to homogeneity, has been used as a substrate to follow the purification of B-50 phosphatase activity. B-50 phosphatase activity can be solubilized from synaptic membranes with 0.5% Triton X-100 and 75 mM KCl. Chromatography of the extract on DEAE-cellulose yields enhanced B-50 phosphatase activity.     

The cardioprotector monoHER does not interfere with the pharmacokinetics or the metabolism of the cardiotoxic agent doxorubicin in mice

PURPOSE: Monohydroxyethylrutoside (monoHER) has proved to be a good protector against doxorubicin-induced cardiotoxicity without interfering with the antitumor effect of doxorubicin. The aim of the present study was to determine whether there is a pharmacokinetic interaction between monoHER and doxorubicin which may be involved in monoHER cardioprotection. METHODS: Mice were treated with monoHER (500 mg x kg(-1) i.v.) alone, monoHER 5 min after doxorubicin (10 mg x kg(-1) i.v.), doxorubicin alone and doxorubicin 5 min after monoHER. The levels of monoHER and doxorubicin(ol) in plasma and heart tissue were measured by HPLC 24 h and 48 h after monoHER and doxorubicin administration, respectively. RESULTS: The areas under the concentration-time curves (AUCs) of monoHER and doxorubicin(ol) were not affected by the coadministered drug. No changes were observed in pharmacokinetic parameters such as initial and final half-lives, mean residence time, clearance and volume of distribution of monoHER and doxorubicin(ol) after single or combined administration. CONCLUSION: The cardioprotection of monoHER in mice is not caused by a pharmacokinetic interaction between monoHER and doxorubicin.     

Anatomical distribution of the growth-associated protein GAP-43/B-50 in the adult rat brain

GAP-43 (B-50,F1,pp46) is a neuron-specific phosphoprotein that has been implicated in the development and modulation of synaptic relationships. Although most neurons cease expressing high levels of GAP-43 after the completion of synaptogenesis (Jacobson et al., 1986), certain brain regions continue to have considerable amounts of the protein throughout life (Oestreicher et al., 1986); in at least one such area, the phosphorylation of the protein has been linked with the events that underlie synaptic potentiation (Lovinger et al., 1985). In this study, we used the indirect immunoperoxidase method to map the distribution of GAP-43/B-50 in the brains of 8 adult rats with 2 different antibodies: a monospecific, polyclonal antibody prepared in sheep against the purified protein and an affinity-purified IgG prepared in rabbits. Specific immunoreactivity was found primarily in the neuropil and followed a generally increasing caudal-to-rostral gradient along the neuraxis. Densest staining occurred in layer I of the cortex, the CA1 field of the hippocampus, and in a continuum of subcortical structures that included the caudate-putamen, olfactory tubercle, nucleus accumbens, bed nucleus of the stria terminalis, amygdala, and medial preoptic area-hypothalamus. In the brain stem, staining was seen in the central gray and in ascending visceral relay nuclei, but was essentially absent in areas related to ascending somatosensory information (e.g., the cochlear nuclei or vestibular complex) and motor control (e.g., nucleus ruber or the motor nuclei of the cranial nerves). Staining in dorsal thalamus was likewise modest in most somatosensory and somatomotor relay nuclei, but dark in certain other structures (e.g., mediodorsal nucleus, lateral complex). This distributional pattern raises the question of whether synapses in all areas containing high levels of GAP-43/B-50 are capable of undergoing functional plasticity, or whether the protein may function in some of these areas in some other capacity (e.g., general signal transduction).